The present invention claims the benefit of Korean Patent Application No. P2000-83096 filed in Korea on Dec. 27, 2000, which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a light source for a display device, and more particularly, to a flat luminescent lamp and a method for manufacturing the same.
2. Discussion of the Related Art
Ultra thin sized flat panel displays having a display screen with a thickness of several millimeters or less, and in particular, flat panel liquid crystal display (LCD) devices, are widely used as monitors in notebook computers, spacecraft, and aircraft.
In such LCD devices, a passive luminescence LCD device includes a back light positioned at the rear of a liquid crystal panel. The back light increases the weight, power consumption, and thickness of a flat panel LCD device.
The back light used in LCD devices as a light source is generally an arrangement of a cylindrical fluorescent lamp. There are two types of back lights, a direct type and a light-guiding plate type.
In the direct type back light, the fluorescent lamp is mounted under the flat panel LCD. If the fluorescent lamp is too close to the LCD flat panel, the shape of the fluorescent lamp is visible on the LCD screen. Therefore, it is necessary to maintain a distance and position between the fluorescent lamp and the liquid crystal panel. As a result, there is a limitation in reducing the thickness of an LCD device that uses a direct type back light.
Furthermore, a light-scattering means may have to be positioned between the fluorescent lamp and the liquid crystal panel for uniform light distribution. Due to the trend of increased display panel area, the light-emitting area of the back light is also increasing. If the direct type back light has a large sized area, the light-scattering means should have a sufficient thickness to make the light-emitting area have a uniform luminescent intensity. Therefore, the need for uniform light-scattering also limits the thickness reduction of the LCD device using direct type back light.
In the light-guiding plate type back light, a fluorescent lamp is mounted outside the LCD flat panel so that light is dispersed across the back surface of the LCD flat panel using a light-guiding plate. Since the fluorescent lamp is mounted at a side of the light-guiding plate, light passing through a side of the light-guiding plate has to be dispersed across the entire surface of the LCD flat panel. Therefore, luminance is low. Also, for uniform distribution of luminous intensity, advanced optical design and processing technologies are required to manufacture the light-guiding plate.
A high luminance direct type back light has been proposed in which a plurality of lamps are arranged below a display surface or a lamp is bent into a circular shape. Recently, a flat luminescent back light in which a flat surface facing a display surface of a panel is wholly luminescent is being researched and developed. This flat luminescent back light is disclosed in the U.S. Pat. No. 6,034,470.
A related art flat luminescent lamp will be described with reference to the accompanying drawings.
FIG. 1 is a plan view illustrating a related art flat luminescent lamp, and FIG. 2 is a sectional view taken along line I-Ixe2x80x2 of FIG. 1.
As shown in FIGS. 1 and 2, the related art flat luminescent lamp includes a lower substrate 11, an upper substrate 11a, cathodes 10 formed on the lower substrate 11, anodes 10a formed on the upper substrate 11a, four frames 19a, 19b, 19c, and 19d for sealing a discharge space between the lower and upper substrates 11a and 11 by a solder means, such as a glass solder, and a plurality of support rods 21 formed between the lower and upper substrates 11 and 11a. The support rods 21 are made of glass material so as not to interrupt emission of the visible light.
The anodes 10a are formed in sets of pairs between support rods at constant intervals. The cathodes 10 are formed on the lower substrate 11 between the sets of pairs anodes 10a. The cathodes 10 and the anodes 10a are coated with a dielectric material (not shown), and an external voltage is applied to the cathodes 10 and the anodes 10a through lead lines 13 and 13a, respectively.
Surfaces of the upper substrate 11a and lower substrate 11 facing the discharge space are coated with a fluorescent material (not shown). Within the discharge space is a Xe gas for creating plasma that emits ultraviolet (UV) rays. The emitted UV rays collide with the fluorescent material formed on the upper and lower substrates 11a and 11. The collision of the UV rays with the fluorescent material generates visible light.
As shown in FIG. 2, the cathodes 10 are formed on the lower substrate 11 of glass material, and a first dielectric material layer 12 is formed on the lower substrate 11 and the cathodes 10. A reflecting plate 14 is formed on the first dielectric material layer 12 and a first phosphor layer 15 is formed on the reflecting plate 14. The reflecting plate 14 serves to prevent the visible light from leaking out the rear of the lower substrate 11. The anodes 10a that induces the plasma discharge together with the cathodes 10 are formed on the upper substrate 11a of glass material. The cathodes 10 and the anodes 10a are formed by silk printing or vapor deposition process.
A second dielectric material layer 12a is formed on the upper substrate 11a and the anodes 10a. A second phosphor layer 15a is formed on the second dielectric material layer 12a. On the upper and lower substrates 11a and 11, frames 19a, 19b, 19c, and 19d are formed to seal the upper and lower substrates 11a and 11 by a glass solder.
In the aforementioned related art flat luminescent lamp, if a voltage is applied to the cathodes 10 and the anodes 10a through the respective lead lines 13 and 13a, Xe gas forms plasma in the discharge space between the cathodes 10 and the anodes 10a and emits UV rays. The UV rays collide with the first and second phosphor layers 15 and 15a, causing the phosphor layers to luminesce, so that the visible light is emitted.
However, the related art flat luminescent lamp has several problems. Since four frames and a number of support rods are required to seal the lower and upper substrates, a large number of parts for manufacturing the lamp are required and thus, processing steps are complicated. Furthermore, the large number of parts increases the weight and size of the lamp.
Accordingly, the present invention is directed to a flat luminescent lamp and a method for manufacturing the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a flat luminescent lamp and a method for manufacturing the same, in which light weight, thin size and high luminance can be obtained.
Another object of the present invention is to provide a flat luminescent lamp and a method for manufacturing the same, in which discharge efficiency can be maximized.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the scheme particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, a flat luminescent lamp according to the present invention includes first and second substrates, each having a plurality of concave and convex portions on a surface; first and second electrodes alternately formed on the convex portions of the first substrate at constant intervals; a dielectric layer formed on the first substrate, and on the first and second electrodes; first and second phosphor layers respectively formed on the dielectric layer and the second substrate; and wherein the first and second substrates are attached to each other with their surfaces having the plurality of concave and convex portions facing each other.
In another aspect of the present invention, a method for manufacturing a flat luminescent lamp having first and second substrates, the method including the steps of etching the second substrate to form a plurality of concave and convex portions on one side of the second substrate; forming first and second electrodes alternately on the first substrate at constant intervals; etching the first substrate between the first and second electrodes to a predetermined depth in order to form a plurality of concave portions in the first substrate; forming a dielectric layer on the first substrate, and on the first and second electrodes; forming first and second phosphor layers respectively on the dielectric layer and the second substrate; and attaching the first and second substrates to each other so that the concave portions of the first substrate substantially correspond to the concave portions of the second substrate.
In other aspect of the present invention, a method for manufacturing a flat luminescent lamp includes the steps of forming first and second substrates, each respectively having a plurality of concave and convex portions on one side; forming first and second electrodes alternately formed on the convex portions of the first substrate; forming a dielectric layer on the first substrate, and on the first and second electrodes; forming first and second phosphor layers respectively on the dielectric layer and the second substrate; and attaching the first and second substrates to each other so that the concave and convex portions of the first substrate respectively correspond to the concave and convex portions of the second substrate.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.